import thenFS from "then-fs"
thenFS.readFile('./txt/a.txt', 'utf8').then(res => {
  console.log(res)
  return thenFS.readFile('./txt/b.txt', 'utf8')
}).then(res => {
  console.log(res)
  return thenFS.readFile('./txt/c.txt', 'utf8')
}).then(res => {
  console.log(res)
  
})